Jack hammer

ABSTRACT

An improved manually actuated self-energizing jack hammer or driver useful as a demolition tool, a compactor, a post or pile driver, a digging tool and the like, composed of an inner anvil tube or barrel receiving a post or pile therein or mounting a tamper, a breaker, a cutter, a digger or the like tools and a tubular ram or hammer telescoped over and guided on the barrel with a recoil spring between the anvil and hammer for lifting the ram after it delivers a hammer blow to the anvil barrel. The inner tube or anvile barrel separates and insulates the driver member such as a fence post or tool from contact with the hammer ram and at the same time guides the ram to insure maximum direct delivery of force from the ram to the tool or post. Handles are provided on the ram for convenient grasping by a single operator to impart a rhythmic reciprocation to the ram aided by the recoil spring to deliver maximum impact blows through the anvil barrel to the tool or post with minimum manual effort. The telescoped barrel tube and ram tube are preferably non-circular in crosssection to prevent relative rotation of the tubes and a heavy hard steel hammer head is secured in the open top of the ram tube preferably in non-mating relation to provide an air vent. The guide tube or barrel also preferably has a heavy hard steel head on the top end thereof providing an anvil receiving the blows from the hammer head. A lock bolt is provided to selectively hold the tubes in telescoped relation.

United States Patent 1 Deike JACK HAMMER [75] Inventor: Robert F. Deike,Cheyenne, Wyo.

[73] Assignees: William H. Chamberlain; Anna B.

Chamberlain, Cheyenne, Wyo. part interest to each [22] Filed: July 19,1973 [21] Appl. No.: 163,696

Related U.S. Application Data, [63] Continuation-impart of Ser. No.123,787, March 12,

Primary Examiner-James A. Leppink Attorney-Carltonl-lill, .1. ArthurGross et al.

57 j ABSTRACT An improved manually actuated self-energizing jack [11]3,747,690 [451 July 24,1973

hammer or driver useful as a demolition tool, a compactor, a post orpile driver, a digging tool and the like, composed of an inner anviltube or barrel receiving a post or pile therein or mounting a tamper, abreaker, a cutter, a digger or the like tools and a tubular ram orhammer telescoped over and guided on the barrel with a recoil springbetween the anvil and hammer for lifting the ram after it delivers ahammer blow to the anvil barrel. The inner tube or anvile barrelseparates and insulates the driver member such as a fence post or toolfrom contact with the hammer ram and at the same time guides the ram toinsure maximum direct delivery of force from the ram to the tool orpost. Handles are provided on the ram for convenient grasping by asingle operator to impart a rhythmic reciprocation to the ram aided bythe recoil spring to deliver maximum impact blows through the anvilbarrel to the tool or post with minimum manual effort. The telescopedbarrel tube and ram tube are preferably non-circular in crosssection toprevent relative rotation of the tubes and a heavy hard steel hammerhead is secured in the open top of the ram tube preferably in non-matingrelation to provide an air vent. The guide tube or barrel alsopreferably has a heavy hard steel head on the top end thereof providingan anvil receiving the blows from the hammer head. A lock bolt isprovided to selectively hold the tubes in telescoped relation.

14 Claims, 11 Drawing Figures PAIENTED SHEU 2 OF 2 INVENTOR. E054??? EDtV/(f JACK HAMMER RELATED APPLICATION This application is acontinuation-in-part of my U.S. Pat. application, Ser. No. 123,787 filedMar. 12, 1971 entitled Manually Actuated Jack Hammer.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to improvements in jack hammers disclosed in my aforesaid parentapplication, Ser. No. 123,787 filed Mar. 12, 1971, dealing with guidebarrel and ram configurations, a lock for the barrel and ram, and areinforced shock absorbing handle arrangement. More specifically thisinvention provides a jack hammer composed of telescoped oval metal tubeswith the inner tube having an anvil head receiving blows from a hammerhead secured to the outer tube, with a spring expanding to separate thehead and anvil and elongated handles secured at their top and bottomends to opposite sides of the outer tube.

SUMMARY OF THE INVENTION The improved driver or jack hammer provided bythis invention has telescoped flattened cylindrical or oval metal tubesin sliding relation with an anvil head bottom end or guide means forreceiving a post or pile projecting through the inner. tube to engagethe anvil head thereof. Additional guides may be provided adjacent thehead to center the post in the tube.

The handles extend verticallyin spaced relation from the opposite flatfaces of the outer or ram tube and are turned inwardly at their top andbottom ends to be attached to these faces. To further rigidify thehandles with minimum transfer of shock from the'ram tube and to alsoprovide a carrier for the locking bolt, gusset plates are welded to theram tube between the top and bottom ends of the handles and carry metalchannels along their top edges which receive cylindrical tubes or pipeswelded at their outer ends to the handles and extending into spacedrelation from the ram tube. Bolts connect these pipes or tubes to theangle strips. One of the pipes receives a slide bolt and has a bayonetslot in its top'face for a bolt pin. The bolt is spring urged to projectthrough a hole in the ram tube and engage a hole or recess in the guidebarrel or tube. The end of the bolt is bevelled in a downward directionso that the guide barrel when pushed into the ram tube will depressthe'bo lt until its aperture orrecess registers therewithflwhereupon thespring will urge the bolt into locked relation with the inner tube thusholding the two tubes in a desired telescoped position.

The spacing of the pipes from the ram tube and the connection of thepipes to the ram tube through bolts provides a shock absorbing mountingbetween the ram tube and the central portions of the handles. Theinwardly bent end portions of the handles also provide shock absorbingconnections between the handles and ram tube. To further insulate theoperator from shock, the handles can be surrounded by resilient rubberor plastic grips.

The driver head is preferably in the form of a heavy elongated cylinderwith a closed end providing a recess for the recoil spring. Thiscylinder is welded along its length in the top end of the ram tube andair relief chambers are thus provided on opposite sides of the headbetween the elongated ends of the flattened or oval ram tube and theouter cylindrical wall of the driver head.

It is therefore an object of this invention to provide improvement onthe manually actuated jack hammer disclosed and claimed in my aforesaidparent application, Ser. No. 123,787 filed Mar. 12, 1971.

Another object of the invention is to provide a jack hammer withtelescoped oval anvil and ram tubes.

A further object of the invention is to provide a jack hammer which hasan inner guide tube with an anvil block on its top end and a toolcarrying chuck or post guide at its bottom end surrounded by and guidinga ram tube having a hammer head at its top end impacting against theanvil together with a compression recoil spring between the anvil andhammer head.

A further object of the invention is to provide an improved shockabsorbing handle construction for jack hammers.

A still further object of this invention is to provide a lock for thetelescoped tubes of jack hammers to maintain the same in telescopedposition during periods of non-use.

A still further object of the invention is to provide an improved hammerhead and ram tube arrangement for a jack hammer which will vent air fromthe tube.

Other and further objects of this invention will be apparent to thoseskilled in this art from the following detailed description of theannexed sheets of drawings which, by way of preferred examples,illustrate several embodiments of the invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a verticalcross-sectional view,with parts in elevation, of a jack hammer according to this inventionshowing the parts in lowered striking position;

FIG. 2 is a view similar to FIG. I but showing the .parts in raised orrecoiled position;

FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1;

FIG. 4 is a crosssectional view taken along the line IVIV of FIG. 1;

FIG. 5 is a cross-sectional view taken along'the line V--V of FIG. 1;

FIG. 6 is a cross-sectional view taken along the line Vl-Vl of FIG. 1with the bolt separated from the tube;

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 5;

FIG. 8 is an enlarged longitudinal cross-sectional view of the bottomend of the guide or anvil tube equipped with a removable chuck carryinga tool according to this invention; A

FIG. 9 is a transverse cross-sectional view taken along the line IXIX ofFIG. 8;

FIG. 10 is an elevational view of a modified jack hammer havingcylindrical ram and anvil tubes held in nomrotatable telescoped relationby lugs on the anvil tube riding in slots in the ram tube; and

FIG. 11 is a transverse cross-sectional view taken along the line XI-XIof FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The jack hammer of FIGS. 1 and2 includes an elongated metal ram tube 11 telescoped over and guided onan elongated anvil post or tool receiving tube 12. The ram tube 11 has aheavy driver head tube or hammer l3 welded in the upper end thereof. Thetop end of the driver head or hammer is closed by a heavy disk 14 weldedin the tube 13.

A heavy anvil head is welded in the upper end of the tube 12.

A helical compression spring 16 extends through the driverhead 13 andhas its top end coil secured to the disk 14 by a nut and bolt assembly17. In its free state the bottom end of the spring 16 projects beyondthe hammer 13 for a number of turns and the bottom end coil of thespring overlies the anvil head 15 without being secured to the head. Asshown in FIG. 1, the spring 16 is compressed completely within thedriver head 13 when this head delivers the impact blow to the anvil head15. In this compressed condition, of course, the spring is loaded torecoil the ram tube upwardly to the FIG. 2 position after it deliversits impact blow so that the next impact blow is delivered to the anvilhead l5upon applicationof downward force to the ram tube by theoperator.

As shown in FIG. 3, the tubes 11 and 12 are flattened cylinders or ovalshaped and are infree sliding mated relation so that they cannot rotaterelative to each other. The ram tube 11 has flat opposite side faces 11aand the anvil tube 12 has mating flat side faces 12a.

As shown in FIG. 4 the cylindrical driver or hammer head 13 is welded tothe side faces 11a of the ram tube 11 along weld bonds 18. Since thehead 13 is cylindrical and the tube 11 is oval, air vent passages 19 areprovided through the top of the tube 11 on both sides of the head 13. I

As shown in FIGS. 1 to 3, the anvil head 15 is reinforced by bevelledcurved gusset plates 20 welded to the underface of the head 15 and tothe inner side walls 12a of the tube 12. These plates 20 converge fromthe flat side walls of the tube 12 to the head, 15 and surround acentral area 21 of the head (FIG. 3) to guide a fence post F.P. to thecenter of the tube 12, as will be more fully hereinafter described.

The opposite flat side faces 11a, 11a of the ram tube 1 1 each have ahandle 22 secured thereon. Each handle 22 has an' elongated verticalportion 22a spaced outwardly from and parelleling the side faces 11a,11a of the tube 11 with inturned top and bottom end portions 22b boltedto brackets 23 which are welded to the side faces Illa, 11a and divergeat about a 45 angle outwardly, therefrom. Bolts 24 extend through theends of the handle portions 22b and through the brackets 23 receivingnuts on the inner ends thereof to unite the handles to the tube 11."

As shown in FIGS. 1 and 2, the top end portions 22b of the handles areabout level with the top end of the tube 11 while the bottom endportions 22b of the bandles are'adjacent the bottom end of the tube 11.In this manner, the vertical portions 22a of the handles extendsubstantially the entire length of the tube 11, but it should beunderstood that the handle length may be shortened if desired. Longhandles are preferred so that the flat side walls 11a of the tube 11.These pipes 26 I rest in horizontal channels 27 carried by gusset plates28 welded to the flat faces 1 la of the tube 1 1 and to the divergentsides of the channels, thereby providing a rigid trough projectinglaterally from the tube and receiving the pipes 26. Bolts 28a extendthrough the pipes and slots in the channels. Nuts on these bolts aretightened against the channels to provide a shock absorbing connectionbetween the pipes and channels.

One of the pipes 26 slidably supports a lock bolt 29 spring pressed by aspring 30 out of the inner end of the pipe. The flat face 11a of thetube 1 1 adjacent this pipe has a hole 11b therethrough into which thepipe freely projects in spaced relation from the face wall. The anvil ortool receiving tube 12 has a hole 12b adapted to register with the openend of the pipe and receives the lock bolt 29 therein to hold the tubes11 and 12 in telescoped position..

The forward end of the lock bolt 29 is downwardly bevelled at 29a toprovide a latch that will ride on the tube 12 to depress the bolt intothe pipe 29 until the hole 12b can receive the bolt.

The top face of the pipe 26 receiving the bolt 29 has a bayonet slot 26atherein and a bolt pin 31 projects from the bolt 29 through this slot sothat the operator may retract the bolt and lock it in the notch of thebayonet slot to hold it in retracted position or may release the pinfrom the notch so that the bolt will lock the tube 12in the tube 11.

As shown in FIGS. 8 and 9, the bottom end of the anvil or tool receivertube 12 may receive a tool chuck 32 or, as shown in FIGS. 1 and 2, mayreceive a post guide 33.

The tool chuck 32 is a heavy hard steel block with an oval recess 34 inthe top face thereof receiving the bottom end of the tube 12. Wing bolts35 are threaded through the block and through holes 126 in the end ofthe tube 12 to lock the chuck to the bottom of the tube. The chuck has ahexagonal hole 36 therethrough and an enlarged cylindrical bottom recess37 with a fragmental spherical shoulder 37a converging to the hexagonalhole 35.

A tube 38 extends at a steep angle through the side wall of the chuckblock 32 to open into the recess 37 below the shoulder 37a. A pair ofvsteel balls 30 separated by and connected to a spacer rod 39a areslidably mounted in the tube 38. A stop pin 40 projects into the tube 37between the steel balls 38 to limit the extent of movement of the ballsin the tube.

A tool 41 such as a concrete breaking chisel is releasably retained inthe chuck 32 and has a hexagonal top pin end 42 fitting in the hole 36thereby holding the tool against rotation relative to the chuck. A head43 on the tool fits freely in the cylindrical recess 37 and seatsagainst the shoulder 37a. This head 43 has a bottom face 44 engaged bythe leading steel ball 39 in the tube 38 thereby retaining the tool inthe chuck. The shank 45 of the tool depends beyond the bottom end of thechuck to terminate in a cutting point or chisel edge 46 below the chuck.

To mount the tool 41 in the chuck, it is only necessary to insert thehexagonal pin end 43 in the hole 36 causing the head 43 to depress theprojecting steel ball 39 back into the tube 38 until the head clears theball, whereupon the ball will drop underneath the face 44 to lock thetool in the chuck. When it is desired to remove the tool from the chuck,it is only necessary to retract the ball 39 from under the face 44of'the tool head 43.

The chuck 32 may be easily replaced with the post guide 33 of FIGS. 1and 2 which has a recess 33a to receive the end of the tube 12 and thesame wing bolts 35 to lock the chuck to the tube. The chuck 33, however,has a through hole 47 shaped .to slidably and snugly receive the fencepost RP. therethrough for guiding the post centrally in the tube 12. Asalso shown in FIG. 1, the upper end of the fence post is guided to thecentral area 21 of the anvil head 15 by the bevelled gussets 20.

in the modified jack hammer 50 of FIGS. and 11 a cylindrical ram tube 51is telescoped over a cylindrical anvil tube 52. The tube 51 haselongated slots 53 in diametrically opposite sides thereof extendingfrom adjacent the top of the tube to adjacent the bottom thereof. Thetube 52 has lugs 54 near the top end thereof projecting laterallytherefrom into these slots and freely slidable therein. The two tubesare thus slidably keyed together and the outer tube 51 can be lifted topull the inner tube 52 therewith when the lugs 54 engage the bottoms ofthe slots 53. The lugs 54 can be integrally welded to the sides of thetube 52 so as not to obstruct the tube interior for receiving a fencepost.

Alternatively, when the jack hammer 50 is to be used as a breaking toolor digger where the tube 52 does not receive a post or pile, holes 55can be provided at spaced intervals along the length of the tube toselectively receive pins 56 which extend into the slots 53 to limit orcontrol the length of the working stroke of the ram 51 as desired. Thusif it is desired to limit the amount the tube 52 can project from thetube 51, a pin 56 can be positioned closer to the bottom of the tube 52so that it will contact the bottom of the slots 53 when the tube 52extends from the tube 51 a desired amount. Two spaced pins could besimultaneously used to limit the extent of both the lifting and loweringstroke of the ram tube 51 with'one pin contacting the tops of the slots53 at the end of the lifting stroke and the other contacting the bottomsof the slots after the impact blow to facilitate lifting of the tool 41'carried by the chuck 32.

The modified hammer 50 can otherwise have the same construction andcomponents as the hammer 10.

To operate the jack hammers of this invention, it is only necessary tomount the desired tool 41 in a chuck such as 32 or to drop the anvilguide tube 12 or 52 over a fence post guided into the tube by a chucksuch as 33. Then, asingle operator merely grasps the handles 22 at aconvenientlevel, raises the ram tube 11 or 51 to a convenient height anddrops it with a downward thrust force whereupon the spring 16 willinitially compress and then the driver head 13 will strike the anvil 15to deliver a hammer blow to the anvil guide tube 12 or 52 which in turntransfers this blow either to the tool or to a the fence post. Thecompressed spring then expands to recoil the tube 11 or 51 upwardly onthe tube 12 or $2 positioning it for thenext downward thrust by theoperator. A rhythm is soon built up enabling the operator to exertmaximum impact blows on the tool or fence post with minimum manualeffort.

It will be understood that the tool, fence post or other work piecebeing acted upon is never directly engaged by the hammer head since theblow from the hammer head is always transmitted to the anvil and theanvil tube isolates the hammer head from the tool or work piece. It willalso be understood that the anvil tube acts as a guide insuring theapplication of the full impact blow on the tool or work piece oneachstroke of the ram tube. Thus, there can be no canting ormisalignment of the ram tube relative to the tool or work piece.

cl claim as my invention: h I i l. A driver tool which comprises ahollow guide tube having an anvil head secured to the top end thereofand a chuck secured to the bottom end thereof, a hollow driving ram tubetelescoped over said guide tube in non-rotatable relation therewithhaving a hammer head adapted to impact against the anvil head of saidguide tube, a compression spring between the hammer head and anvil'headeffective to recoil the hammer head away from the anvil head after eachblow of the hammer head against the ram head, said spring having a freeextended length substantially less than the stroke of the ram tube onthe guide tube, and elongated handles secured to the ram tube andextending in laterally spaced relation from opposite sides of the ramtube for a substantial portion of the length of the ram tube.

2. The driver tool of claim 1 wherein the guide tube and the ram tubehave non-circular cross-section configurations in mating relationpreventing relative rotation of the tubes.

3. The driver tool of claim 1 wherein the guide tube and the ram tubehave oval cross-sectional shapes in mated non-rotating engagement.

4. The driver tool of claim 1 wherein the chuck is removable.

5. The driver tool of claim 1 wherein the guide tube has post guidemeans therein directing a post to engage the central portion of theanvil head.

6. A jack hammer which comprises telescoped tubes in non-rotating matedengagement, an anvil head secured to the inner tube, a hammerheadsecured to the outer tube, a coil spring between said heads effective torecoil the hammer head away from the anvil head after each blow of thehammer head against the anvil head, said spring having a free extendedlength less than the stroke of the outer tube on the inner tube, andelongated handle means secured to the outer tube having grippingportions in laterally spaced relation from opposite sides of the outertube.

7. The jack hammer of claim 6 wherein said tubes are oval shaped.

8 The jack hammer of claim 8 wherein the outer tube is oval shaped, thehammer head is cylindrical and extends into the upper end of the outertube and air vent passages are provided through the top end of the outertube between the cylindrical hammer head and the oval tube.

9. The jack hammer of claim 8 wherein the tubes are cylindrical withcooperating lug and slots holding the tubes against relative rotation.

10. The jack hammer of claim 8 wherein the outer tube has elongatedslots terminating adjacent the ends thereof and the innertubehasprojections riding in the' slots.

11. The jack hammer of claim 10 wherein the projections are the ends ofa removable pin traversing the inner tube.

12. A driver tool which comprises a hollow guide tube having an anvilhead secured to the top end thereof and a chuck secured to the bottomend thereof, a hollow driving ram tube telescoped over said guide tubein non-rotatable relation therewith having a hammer head adapted toimpact against the anvil head of said guide tube, a compression springbetween the hammer head and anvil head effective to recoil the hammerhead away from the anvil head after each blow of the hammer head againstthe ram head, elongated handles secured to the ram tube and extending inlaterally spaced relation from opposite sides of the ram tube forsubstantial portion of the length of the ram tube, and shock absorbingmeans connecting the handles to the ram tube.

13. A driver tool which comprises a hollow guide tube having an anvilhead secured to the top end thereof and a chuck secured to the bottomend thereof, a hollow driving ram tube telescoped over said guide tubein non-rotatable relation therewith having a hammer head adapted toimpact against the anvil head of said guide tube, a compression springbetween the hammer head and anvil head effective to recoil the hammerhead away from the anvil head after each blow of the hammer head againstthe ram head, elongated handles secured to the ram tube and extending inlaterally spaced relation from opposite sides of the ram tube for asubstantial portion of the length of the ram tube, a lock bolt carriedby a handle, said ram tube having an aperture freely receiving said lockbolt, and said guide tube having a recess receiving the lock bolt whenthe recess is aligned with the ram tube aperture whereby the ram tubeand guide tube are locked together in telescoped relation.

14. A jack hammer which comprises telescoped tubes in non-rotating matedengagement, an anvil head secured to the inner tube, a cylindricalhammer head secured to the outer tube, a'coil spring between said headsextending into the hollow interior of the cylindrical head effective torecoil the hammer head away from the anvil head after each blow of thehammer head against the anvil head, and elongated handle means securedto the outer tube having gripping portions in laterally spaced relationfrom opposite sides of the outer tube.

1. A driver tool which comprises a hollow guide tube having an anvil head secured to the top end thereof and a chuck secured to the bottom end thereof, a hollow driving ram tube telescoped over said guide tube in non-rotatable relation therewith having a hammer head Adapted to impact against the anvil head of said guide tube, a compression spring between the hammer head and anvil head effective to recoil the hammer head away from the anvil head after each blow of the hammer head against the ram head, said spring having a free extended length substantially less than the stroke of the ram tube on the guide tube, and elongated handles secured to the ram tube and extending in laterally spaced relation from opposite sides of the ram tube for a substantial portion of the length of the ram tube.
 2. The driver tool of claim 1 wherein the guide tube and the ram tube have non-circular cross-section configurations in mating relation preventing relative rotation of the tubes.
 3. The driver tool of claim 1 wherein the guide tube and the ram tube have oval cross-sectional shapes in mated non-rotating engagement.
 4. The driver tool of claim 1 wherein the chuck is removable.
 5. The driver tool of claim 1 wherein the guide tube has post guide means therein directing a post to engage the central portion of the anvil head.
 6. A jack hammer which comprises telescoped tubes in non-rotating mated engagement, an anvil head secured to the inner tube, a hammer head secured to the outer tube, a coil spring between said heads effective to recoil the hammer head away from the anvil head after each blow of the hammer head against the anvil head, said spring having a free extended length less than the stroke of the outer tube on the inner tube, and elongated handle means secured to the outer tube having gripping portions in laterally spaced relation from opposite sides of the outer tube.
 7. The jack hammer of claim 6 wherein said tubes are oval shaped.
 8. The jack hammer of claim 8 wherein the outer tube is oval shaped, the hammer head is cylindrical and extends into the upper end of the outer tube and air vent passages are provided through the top end of the outer tube between the cylindrical hammer head and the oval tube.
 9. The jack hammer of claim 8 wherein the tubes are cylindrical with cooperating lug and slots holding the tubes against relative rotation.
 10. The jack hammer of claim 8 wherein the outer tube has elongated slots terminating adjacent the ends thereof and the inner tube has projections riding in the slots.
 11. The jack hammer of claim 10 wherein the projections are the ends of a removable pin traversing the inner tube.
 12. A driver tool which comprises a hollow guide tube having an anvil head secured to the top end thereof and a chuck secured to the bottom end thereof, a hollow driving ram tube telescoped over said guide tube in non-rotatable relation therewith having a hammer head adapted to impact against the anvil head of said guide tube, a compression spring between the hammer head and anvil head effective to recoil the hammer head away from the anvil head after each blow of the hammer head against the ram head, elongated handles secured to the ram tube and extending in laterally spaced relation from opposite sides of the ram tube for substantial portion of the length of the ram tube, and shock absorbing means connecting the handles to the ram tube.
 13. A driver tool which comprises a hollow guide tube having an anvil head secured to the top end thereof and a chuck secured to the bottom end thereof, a hollow driving ram tube telescoped over said guide tube in non-rotatable relation therewith having a hammer head adapted to impact against the anvil head of said guide tube, a compression spring between the hammer head and anvil head effective to recoil the hammer head away from the anvil head after each blow of the hammer head against the ram head, elongated handles secured to the ram tube and extending in laterally spaced relation from opposite sides of the ram tube for a substantial portion of the length of the ram tube, a lock bolt carried by a handle, said ram tube having an aperture freely receiving said lock bolt, and said guide tube having a recess receiving the lock bolt when the recess is aligned witH the ram tube aperture whereby the ram tube and guide tube are locked together in telescoped relation.
 14. A jack hammer which comprises telescoped tubes in non-rotating mated engagement, an anvil head secured to the inner tube, a cylindrical hammer head secured to the outer tube, a coil spring between said heads extending into the hollow interior of the cylindrical head effective to recoil the hammer head away from the anvil head after each blow of the hammer head against the anvil head, and elongated handle means secured to the outer tube having gripping portions in laterally spaced relation from opposite sides of the outer tube. 